"It's simple," James said as the Heat prepared for Tuesday's home game against the Milwaukee Bucks. "These first seven games, we're playing like s--- defensively. It's that simple. We're not a sugarcoat team. We came in and got right down to it. We're terrible on defense, and we've got to change that."
James' comments came on the heels of the Heat's 111-110 loss Saturday to the Boston Celtics, who won on a buzzer-beating 3-pointer by Jeff Green after overcoming a four-point deficit in the final 3.6 seconds. The shot from Green capped a relentless performance by the Celtics, who took advantage of Miami's lethargic defensive effort throughout the game.
It's already developing into a disturbing trend for the Heat, who are ranked first in the league in offensive efficiency but just 25th among the NBA's 30 teams in defensive efficiency. Miami also ranks among the bottom third in the league in points allowed, yielding 100.9 per game.
The Heat opened Tuesday's practice with some harsh words from coach Erik Spoelstra and then spent the next two hours working to correct defensive concerns. After the workout, James twice used expletives during his session with reporters when asked the source of the team's poor play.
The early-season problems aren't new for the Heat, who were ranked 26th in points allowed through the end of November last season. That slow start eventually gave way to a 27-game winning streak and culminated in a second straight championship.
But Spoelstra said last season's performance has no bearing on this season's challenge. The Heat spent the first week of training camp in the Bahamas focused exclusively on defensive drills and schemes.
"Regardless of who you are, where you've been, what you've done, what you're doing, you constantly have to work at it," Spoelstra said Monday. "Not only physically. Sometimes it's mentally. It's your preparation. It's your attitude coming into the game. All of those things. We're not playing to our capabilities, so you have to jump right back on top of it."
The stretches of inconsistency have seen the Heat play a poor first half against the Los Angeles Clippers on Thursday, only to smother and frustrate Chris Paul in the third quarter en route to a 102-97 victory. On Saturday against Boston, the Heat reverted to some bad habits and saw the Celtics shoot 52 percent from the field and 48 from 3-point range, and hold a 15-5 edge in fast-break points.
It also marked the second time in six games an opponent has scored at least 111 points against the Heat, who opened the season with an impressive 107-95 victory against the Chicago Bulls.
James said many factors have contributed to the lapses, including key players being in and out of the lineup dealing with injuries and other matters.
Three starters have missed games already this season, and James has been playing through back pain since midway through training camp.
But that hasn't stopped Miami from playing well offensively. James said the loss to Boston on a last-second shot should serve as a wake-up call.
"We're playing good basketball at times, but besides the Chicago game, we haven't played a full game," James said. "But the good thing about this team, we came right in here and knew exactly what kind of [work] day it was going to be. [Spoelstra] gave it to us direct. We all like constructive criticism. We got on each other and we probably had one of the best practices we've had in a while."